They stole 100 Warren breed chickens from a rural property in Milby near Boroughbridge.
The theft happened between 8.30pm on Wednesday and 8.30pm on Thursday.
Warrens are the chickens normally used commercially for egg-laying.
As well as producing large amounts of eggs - around 320 a year - they are also said to be friendly, inquisitive and easy to handle.
They cost around £10 to £15 for a "point of lay" bird - ie one that has yet to lay an egg.
In other news: In pictures: Racegoers accessorise with umbrellas at Aintree's Ladies DayNorth Yorkshire Police is appealing for anyone with information to contact them on 101.